Excerpt: By the time officials in Flint, Mich., declared a state of emergency in response dangerously high levels of lead in the city’s drinking water in mid-December of 2015, residents had been complaining to each other about discolored and foul-smelling drinking water for more than a year. That time lag, between residents identifying a potential hazard and government officials taking action, shocked Pooja Chandrashekar, A.B. ’18, a biomedical engineering concentrator at the Harvard John A. Paulson School of Engineering and Applied Sciences. “That was when we first conceived the idea of leveraging social media data, media reports, and Google trends data to come up with an environmental monitoring system,” she said. “We thought that, by using non-traditional data sources, we could get a better idea of what people are discussing online and what kinds of things are raising red flags for them.”